Reeling from a second straight loss to Barack Obama, a flailing Republican Party in 2013 found its culprit: Mitt Romney's callous tone toward minorities. Instead of being doomed to irrelevance in a changing America, the party would rebrand as a kinder, more inclusive GOP. They called their findings an "autopsy," and party leaders from Paul Ryan to Newt Gingrich welcomed it with fanfare.

Pundits laughed it off as the buffoonish ramble of a fringe New York billionaire on that March 2013 day, but what Trump didn’t say — and what the party establishment couldn’t have imagined — is that, three years later, he would be the one on the verge of making that death wish come true. The billionaire has not only ignored the report’s conclusions, he has run a campaign that moved the party in the exact opposite direction.

Now, with Trump’s GOP takeover fully underway, interviews with four co-authors of the 2012 autopsy and 10other Republican leaders reveal a party establishment terrified that Trump is not only repeating the party’s failures — he’s destroying the party in the process. And while the leaders continue to insist that their report laid out the Republican Party’s best chance of victory, they fear Trump’s dominance will tear the party apart before they ever get a chance to put it in play.

"Swing voters would flock away from him in droves," said Henry Barbour, one of the autopsy’s authors. And as for Trump’s claim that his working-class appealing will bring back Reagan Democrats, the veteran Mississippi Republican operative is unmoved: "He’s chasing some ghost that I don’t think exists anymore."

After mounting for months, tension exploded Thursday with the return of Romney himself, who ripped Trump as a “fraud” and declared him anathema to what the Republican Party aspired to be. It’s part of a last-ditch effort by Romney, 2008 GOP presidential nominee John McCain and other party leaders to snatch the primary back from Trump before he rolls through to the general election.

But members of the GOP establishment concede that they have little influence over Trump, and have thus far been unable to exert much leverage in their party’s primary: “The party itself is less consequential than ever before, and since our shellacking in 2012, the tribal differences are increasingly irreconcilable,” said former Utah Gov. Jon Huntsman. “If Trump prevails, he will have single-handedly upended the old Republican order and built a new movement in its place. The question then will be, is it sustainable?”

For GOP leaders, what’s so vexing about Trump’s campaign is that it’s a photo-negative of everything the autopsy said was needed to win a general election.

The report — the product of 2,600 interviews with voters, experts, party officials and business leaders, as well as a poll of Hispanic Republicans and an online survey of 36,000 stakeholders — was remarkable for its blunt criticism of Republican politics. The party, the report’s five authors argued, had become the realm of "stuffy old men" and spent too much time "talking to itself" rather than engaging new voters. Backing immigration reform, the authors concluded, would be necessary to shed that image. "If we do not, our Party’s appeal will continue to shrink to its core constituencies only," the authors wrote.

Trump trashed that advice on Day One and never looked back. His campaign opened with a speech describing undocumented Mexican immigrants as rapists and murderers, which Trump followed with a call for a ban Muslims entering the U.S. And just days ago, he went on national television and refused to condemn the Ku Klux Klan. (He later disavowed the group and support from former KKK grand wizard David Duke, but his critics say he has still been far too close to white supremacist groups and rhetoric.)

Trump's campaign declined to comment on the lessons of the GOP autopsy. But the day after its release in 2013, he expanded on his critique, delivering a pointed attack that previewed a theme he’d deploy in his primary run. ".@RNC report was written by the ruling class of consultants who blew the election," hetweeted. "Short on ideas. Just giving excuses to donors."

Trump insists his rise is an alternative path to growing the GOP. “Why can't the leaders of the Republican Party see that I am bringing in new voters by the millions — we are creating a larger, stronger party!” he tweeted Wednesday.

But that argument hasn’t quelled the panic among veteran Republicans, who insist that regardless of how far the strategy takes Trump, it’s ultimately a dead end for the party as a whole. Ari Fleischer, an autopsy coauthor and former press secretary to President George W. Bush, added that a Trump loss in November would be validation for the autopsy. “If Trump’s the nominee and he loses spectacularly, I think you’ll actually have a story that says we were right,” he said.

“The fact remains, America’s demography is changing and that won’t stop … So let’s just say Donald Trump wins the election because of his unique appeal to blue-collar Democrats. The report will be valid for his successor most likely,” Fleischer continued. “Demographics is demographics, and what we said remains important.”

Barbour was similarly skeptical about the party’s fate if it disregarded the autopsy’s advice.

“What we advocated for is that the Republican Party be the conservative party, but that we be a welcoming party. That’s always going to be a good idea,” said Barbour. “Could we have advocated more that Republicans needed to do a better job engaging with working-class Americans? Sure, absolutely. But, look, we tried to be very candid in the report, and I think we tried to call a spade a spade.”

It’s not just Trump. The rhetoric on immigration, even from candidates other than Trump, has jolted to the right. Ted Cruzrecently pledged to root out and deport undocumented immigrants on a large scale aftersuggesting in January that he'd take a softer approach. And Marco Rubio, who once embraced immigration reform and embodied much of what the report recommended the GOP become, is also running on an anti-amnesty program — and pledging to rescind Obama’s executive orders on deferred deportation for certain undocumented immigrants.

And there’s another group the report touted that has been largely rejected by the party’s voters: governors.

The autopsy described Republican governors as models for inclusive politics, pointing to their sweeping victories in 2010. But primary voters have proven that their appetite for governors — and for striking a deal on immigration reform — is virtually nonexistent. Of the seven current and former Republican governors who ran for president this cycle, only Ohio Gov. John Kasich remains, and he's dramatically behind in the race.

If the autopsy proves prophetic and the party loses big in 2016, some fear the current Republican coalition won’t get another chance to act on the report’s advice.

A Trump primary win “would precipitate the breakup of the Republican Party. I wouldn’t be a part of it and a lot of people I know wouldn’t be a part of it,” said Pete Wehner, an aide to the last three Republican presidents. “It would take decades to undo it, potentially. The Republican Party is becoming redefined by Trump, and the question is, Can we jerk it back?”

One RNC leader even suggested the party's destruction is already underway.

"The 2012 autopsy is just what you called it — a case study on the dead rather than a clinical review for lessons to be learned with preventive measures outlined for healing/averting future cases of the disease which caused our demise," said Ada Fisher, a committeewoman from North Carolina. "A rebellion is at hand. Bernie Sanders and Donald Trump both reflect this new direction."

What’s all the more frustrating for the report’s authors is that other parts of the party are following their blueprint closely.

The autopsy recommended sweeping changes to the Republican primary process, from fewer debates to a more condensed calendar of nominating contests to reforms to polling. The authors pleaded with Republican leaders to invest in a robust digital strategy and a data program to help target potential voters. It recommended coordinating outside spending to ensure consistent messages among allied PACs and nonprofits.

On these technical counts, the party has mostly gotten high marks. But without solving the riddle of how to coax more minorities into the fold, it may all be for nothing, argued co-author Sally Bradshaw, a senior adviser to Jeb Bush’s failed presidential campaign.

“I think the jury is still out, but it’s not looking encouraging,” she said. “I believe the RNC has made great strides on the data, analytics and mechanics front, and for that [RNC Chairman] Reince Priebus and his team deserve great credit. But if we can’t bring women and minorities to our party with a hopeful and optimistic message about the future — if we can’t show voters how conservative principles will help them rise up out of poverty and provide an opportunity for a better life — then no amount of good data will make a damn bit of difference.”

Some in the establishment are so dismayed at what Trump means that they’re openly musing that a Trump loss in November would be potential step forward for the party, forcing Republicans to accept the conclusions of the 2012 autopsy.

"I’m not prepared to say it would be 'better' for the party to lose, only that it might hasten a modernization that I think is already a couple election cycles overdue," said Fergus Cullen, former chairman of the New Hampshire Republican Party, who said he wouldn't support Trump under any circumstances. "Sometimes, it takes multiple defeats before a majority of a party realizes it needs to adapt to changing times in order to stay relevant. Half the party seems stuck in 1980."

"The Republican Party has to make its own inner peace with the changing demographics in America," added Wehner. "If it runs against Hispanics and other minorities, that ultimately can’t be sustained."

Where some operatives foresaw doom for the party, others described opportunity. Trump may not speak from the same playbook as Republican insiders, they argue, but he's bringing new energy to a party desperate for it.

"I reject that the thesis that Trump is necessarily divisive in the long term. He is divisive in the GOP primary largely because he is challenging the status quo of both the consulting and governing classes," said Jesse Benton, a longtime aide to Ron and Rand Paul. "But as this campaign moves forward, I think it will be up to existing leaders to get over it and work together with Mr. Trump to grow what appears to be a burgeoning movement and make sure that it has a positive, not negative, tone. For example, they must stress that no one is mad at Latinos. The Trump movement must do due diligence to show that they embrace Latinos."

Tim Albrecht, an Iowa based Republican PR consultant and former adviser to Gov. Terry Branstad, suggested Republicans at all levels could benefit if the party can "harness the passion" of Trump voters and turn them into into straight-ticket GOP voters.

Some operatives argued that the party itself is at fault for failing to connect with voters the way Trump has, that leaders should learn from his ability to communicate a persuasive message to grass-roots voters and speak the language of ordinary Americans.

"We needed to find a better message," said Barry Bennett, former campaign manager to Ben Carson who has informally offered advice to Trump. "As Republicans, we always have the inclination to fight the last cycle's wars all over again. We need to be better at listening. Only then will we get better at talking."

Trump, Bennett added, is bringing new voters into the GOP fold, even if they're not the ones the party envisioned. "He is making the tent larger, which is the goal," he said.

Fisher, the North Carolina committeewoman, said it’s for that reason that party leaders should embrace Trump if he becomes the GOP nominee.

"I spend a lot of time in beauty/barbershops, on the block and where ordinary people are," she said. "They like Trump and his in-your-face style. He is viewed as sticking it to 'em. If Trump becomes the nominee then we should accept it and help him win and become a great president. In no case should the party ever hope to lose.”